737 Hydraulics Flashcards
How many hydraulic systems are there?
3
What are the hydraulic systems called?
A, B, Standby
What is the normal hydraulic pressure range?
3000 psi +/- 200 psi, max 3500
What is the purpose of the PTU? When would it operate?
Provide Hydraulic System B pressure sufficient to provide normal rates of operation for the Autoslats and Leading Edge Devices (LED) in the event the Hydraulic System B Engine-Driven Pump output pressure drops
Failure of Sys B
Are there flight deck indications of PTU operation?
NO
What are components specific to the Hydraulic System A?
Ailerons, Rudder, Elevator and Elevator Feel, Flight Spoilers (Two on Each Wing), Ground Spoilers, Alternate Brakes, No. 1 Thrust Reverser, Autopilot A, Normal NWS, Landing Gear, Power Transfer Unit (PTU) A for lAnding gear
What are components specific to the Hydraulic System B?
Ailerons, Rudder, Elevator and Elevator Feel, Flight Spoilers (Two on Each Wing), Leading Edge Flaps and Slats, Normal Brakes, No. 2 Thrust Reverser, Autopilot B, Alternate NWS, Landing Gear Transfer Unit (LGTU), Autoslats, Yaw Damper, Trailing Edge Flaps) B for Brakes and flaps and yaw damper
What does positioning a FLT CONTROL switch to STBY RUD do? looking for the logic
Activates the Standby Hydraulic Pump
Deactivates FLT CONTROL low pressure light Arms STBY hydraulic low pressure light
What is the light logic when this occurs?
Illuminates STBY RUD ON, FLT CONT annunciator, and MASTER CAUTION lights
What would cause the automatic operation of the Standby Hydraulic System?
Loss of A and/or B with flaps extended with wheel speed greater than 60 kts Loss of A and/or B with flaps extended airborne OR: The Force Flight Monitor (FFM) trips STBY SYSTEM -rudder -thrust reversers UNLESS you arm the Alternate Flaps and put the LE devices down
During normal operations, what could cause variations in hydraulic quantity indications?
High demand on the system
What would indicate a hydraulic system requires a refill? When would you see this annunciation, and where is it located?
Quantity below 76%, will show 30 seconds of flaps retracted on the ground.
What pressurizes the Hydraulic System A & B reservoirs?
Regulated bleed air
Which hydraulic reservoirs have a standpipe?
A and B
What quantity percentage do the associated standpipe(s) protect the reservoir(s) down to?
A - 20% enough to protect electric pump
B - 0% but enough for PTU ops only
With zero indicated on the Hydraulic System B quantity indicator, can the PTU still operate?
Yes
When is the Standby HYD LOW QUANTITY (amber) light armed?When would it illuminate?
When the standby reservoir is below 50%
What does a LOW PRESSURE (amber) light indicate? OVERHEAT (amber) light?
LOW PRESSURE = indicate the respective pump output pressure is low.
OVERHEAT = an overheat condition is detected in the respective system.
Does the Hydraulic System A reservoir standpipe protect against a leak in both the engine driven pump and electric motor-driven pump? System B?
System A: If a leak develops in the Engine Driven Pump, the Electric Driven Pump is still available by the Standpipe, providing 20%.
If a leak develops in the Electric Driven Pump, you lose both pumps and hydraulic drops to 0%.
System B: No. Loss of both Engine and Electric Driven Pumps from a leak anywhere in the system.
What indications, if any, would you see in the event of a Standby Hydraulic system leak?Does it affect any other system?
System B would decrease to 70%, affects system B
Should both ELEC hydraulic pump switches be turned on simultaneously?
Precautions?
No, too much of an electrical load. #1 then #2
Need 1675 fuel in each tank for cooling
*T/F? In System B: Extension of the Leading Edge Devices may result in up to 20% drop in hydraulic fluid quantity
TRUE
